Understanding your results
Compare your Water Check results with the Australian Drinking Water Guidelines (ADWG), published by the National Health and Medical Research Council (NHMRC). The guidelines set two kinds of values:
- Health-based values: above this level, drinking the water over a long period may affect your health.
- Aesthetic values: above this level, the water may taste, smell or look unpleasant, or cause staining or scaling, but it isn't expected to be a health risk.
Reading your strip units: Some pads read in mg/L, and others (such as lead) read in ppb. 1 mg/L = 1 ppm = 1,000 ppb (µg/L). The lead guideline of 0.005 mg/L is the same as 5 ppb.
Microorganisims
Health
E. coli
Guideline: Not detected in any 100 mL sample
Any E. coli means the water has recently been contaminated by faeces, for example from birds, possums or rodents on the roof or in the tank. Stop drinking it untreated. Boil it or use another supply, find and fix the source, and disinfect the tank.
Phys-chem parameters
pH
Aesthetic
Guideline: 6.5–8.5
Low pH (acidic) water can corrode pipes and fittings, which can release copper and lead into the water. Rainwater is often slightly acidic. New concrete tanks can push pH higher; up to 9.2 is tolerated.
Total alkalinity
No guideline
Guideline: No ADWG guideline value
Alkalinity is the water's ability to resist changes in pH. Low alkalinity, common in rainwater, often goes with corrosive water.
Total hardness (as CaCO₃)
Aesthetic
Guideline: 200 mg/L
Above 200 mg/L, scale builds up in kettles, hot water systems and pipes, and above 500 mg/L it becomes severe. Very soft water (below about 75 mg/L) can be corrosive to pipes.
Copper
Health
Aesthetic
Guideline: 2 mg/L (health), 1 mg/L (aesthetic)
Usually comes from copper pipes, especially with acidic or soft water. It can cause blue-green staining and a bitter taste.
Lead
Health
Guideline: 0.005 mg/L (5 ppb)
Lead can come from old solder, brass fittings, roof flashings or paints. There is no safe level for children or pregnant women. If your strip shows any colour change for lead, stop drinking the water and confirm with a lab test.
Iron
Aesthetic
Guideline: 0.3 mg/L
Causes a metallic taste and red-brown staining.Â
Manganese
Health
Aesthetic
Guideline: 0.1 mg/L (health), 0.05 mg/L (aesthetic)
Causes black-brown staining and a bitter taste. It's more common in bore water.
Mercury
Health
Guideline: 0.001 mg/L (1 ppb)
Rarely found in tank water. If your strip shows any colour change for mercury, stop drinking the water and confirm with a lab test.
Free & total chlorine
Health
Aesthetic
Guideline: 5 mg/L (health); taste and odour from about 0.6 mg/L
Tank and bore water normally contain no chlorine unless you've disinfected the tank. On town water, a small amount of chlorine is normal and shows the supply is disinfected.
How accurate are test strips? Test strips give a good indication of whether a parameter is well below, near or above the guideline value. They aren't as precise as a laboratory test. If your result is close to or above a guideline value, particularly for a health parameter such as lead, copper, manganese or mercury, confirm it with a NATA-accredited laboratory before making decisions about your water.
Other common concerns
These aren't covered by Water Check kits.
Arsenic
Health
Guideline: 0.01 mg/L
Can occur naturally in some bore water.
Nitrate
Health
Guideline: 50 mg/L for bottle-fed infants under 3 months; up to 100 mg/L for adults and children over 3 months
Comes from fertilisers, septic systems or animal waste, and mainly affects bores.
Nitrite
Health
Guideline: 3 mg/L
Same sources as nitrate.
Fluoride
Health
Guideline: 1.5 mg/L
Can be naturally high in some bore water.
PFAS
Health
Guideline: PFOS 8 ng/L · PFOA 200 ng/L · PFHxS 30 ng/L · PFBS 1,000 ng/L
"Forever chemicals" from firefighting foams and industrial sources. Relevant near airports, defence bases and fire training grounds.
Important
Water Check kits are screening tools. They help you understand your water and decide what to do next. They aren't a replacement for accredited laboratory testing, which is needed for formal or regulatory testing. If you're unsure about a result, contact your local council or state health department.
Source: NHMRC, Australian Drinking Water Guidelines, Version 4.0 (2025).